Work has begun on a massive underground sewerage superhighway in western Singapore - the most ambitious project of its kind here to date.
On track to be completed in 2025, the underground labyrinth of pipes will comprise 40km of deep tunnels and 60km of link sewers, traversing 100km across the western half of Singapore, including the downtown area and some new developments in the Jurong Lake District, Tengah Town and the Greater Southern Waterfront.
Used water will be conveyed via gravity to an integrated used-water and waste-management plant - the future Tuas Nexus - for treatment and recycling into Newater.
Highlighting the economic benefits of DTSS (Deep Tunnel Sewerage System) Phase 2, national water agency PUB said it will allow 150ha of land - the size of about 200 football fields - to be made available, as older existing water reclamation plants and pumping stations around the island are phased out.
These include the conventional water reclamation plants in Ulu Pandan and Jurong, and the intermediate pumping stations.
Work officially began yesterday at a PUB site in Jalan Bahar with the unveiling of the first tunnel-boring machine, which will create tunnels 3.5m in diameter below ground.
The first phase of DTSS was completed in 2008 to serve eastern Singapore.
In the second phase, PUB will break new ground in a bid to make Singapore's water systems more sustainable.
Once tunnelling work is completed, used water from homes, offices and industries will be conveyed via two tunnels - the 30km South Tunnel, which is for domestic use, and the 10km Industrial Tunnel, for industrial use - to the Tuas Nexus.
Phase 2 will cost $6.5 billion, with $2.3 billion devoted to 19 tunnel-boring machines.
Minister for the Environment and Water Resources Masagos Zulkifli officiated the launch of the DTSS Phase 2 tunnel-boring machine yesterday.
"This is another key milestone in one of Singapore's most significant water infrastructure projects. It is a significant and necessary investment to meet our population's long-term water needs," Mr Masagos said.
He added that the DTSS would allow for every drop of used water to be continually reused.
He said: "The DTSS will transform our used water system to support our growing water needs, and ensure an effective and efficient sewerage system for Singaporeans."
This second phase of the DTSS will also be the first time that smart tunnel-monitoring systems and fibre-optic sensors will be used to detect problems before they pose real risks.
For instance, a smart tunnel-monitoring system known as the Shaft and Tunnel Excavation System (Stems) will act as a nerve centre, providing real-time updates on the location of the tunnel-boring machines, making sure that operations throughout the construction period remain safe and run smoothly, with minimal disruption to urban structures above.
There will also be a fibre-optic system in place to monitor the structural integrity of tunnel linings. Additionally, isolation gates will be put in place to allow parts of the tunnel to be sectioned off for repair work.
The DTSS Phase 2 will also be the first project in Singapore to use ventilation equipment called air jumpers, which manage air flow in the tunnel by pushing odorous air farther downstream to be treated at an odour control facility.